You Can Teach Old Dogs New Tricks
Talking about 60’s and 70’s era pommie bikes here, of course. It is amazing how much aftermarket parts and accessories there is available to help your old rattler. Bits to make them go faster, more bits to make them start easier , other bits to make them stay running longer and run for longer periods between service and repair . Also a few bits to make them look pretty. If you know me then you would know I am not interested modern bikes but I actively pursue modifications to my 60’s- 70’s machines to help them run with some of the more “modernish” bikes . These machines built in the seventies or eighties with the benefit of better engineering techniques, like Hondas 4 cyl , are streets ahead of the typical pre ’78 British machines in my shed. I know it may seem a waste of time to most but I do love to engage in a bit of steroid skulduggery on my 60’s & 70’s era mongrels, to give them a leg up. These modifications are only on the non matching specials I build as one wouldn’t tear down a matching number bike to build a special ,would one, hang on, why have all those parts been lying around swap meets for 20-30-40 years, who did this? On the flip side I wouldn’t waste a restoration on a non matching 60 or 70’s bike, what’s the point, no nitpicker would want to give top dollar for a non matcher.
Now, as for reliability, there are a few substitutes out there for points or mags. I’ve got nothing against points or mags as I still have a few machines that use them and when well set up are as good a starter and runner as modern replacements. With the mags as most of you know, with the benefit of modern windings, epoxies and capacitors do the trick bringing them into this century , almost. I use points but mainly in my offset crankshaft machines where electronic ignitions made to order can be expensive. They are relatively low mileage things so only need a check occasionally, although my Commando Triton 70 deg has 4000 miles on points and I have yet to check them. I had great runs from points early on and one situation stands out. It was a case of a breakdown on the way back from Cairns on a Commando. A set of points broke apart and I was able to make it into town on one cylinder. I saw a Lucas sign on an old garage, turns out they had some old stock and although not exactly correct, it was close enough. These points lasted for thousands of miles before I got around to replacing them. I tried the Boyer ignitions early on and was let down twice so I went back to points. Trouble with points now days is finding quality replacement stock ,some of the new offerings don’t seem to hold up that well on the rubbing blocks but regular lube to the points cam helps. A few years later I tried Boyer ignitions again and they were much more reliable and I have either Boyer or Pazon in a lot of my bikes I ride and many I sell. The big problem with going to electronic is the voltage sensitivity . Low batteries are a big problem whereas with points a machine can usually start on the alternator (no battery) if it is in reasonable nick. That is the thing when going to a modern set and forget ignition, quite often a charging system upgrade is called for. The main problem is of course the magnetism of the rotor, over the years it weakens and the output is correspondingly weaker. Usually the stator (winding) is ok unless it has been rubbing (poling) with a loose rotor. Early rotors were 7 pieces cast in a lump with aluminium and they could break up after first becoming loose on its centre. Modern replacements have welded poles to the centre. So if you opt for set and forget ignition remember to check the charge rate and listen for a knock at idle coming from the primary. ( likely a rotor breaking up) With an old generator model twin, an Alton AC genny replacement ( basically a Kubuto tractor unit I believe) is about the only way to get a charge system good enough to carry a magneto electronic replacement system . As well as easier starting , usually, these upgrades now days should add reliability. The Alton has no slip rings or brushes, works just like the alternator in a typical pommie but slim like a 3” genny.. Another somewhat unreliable part is the original regulating, rectifying components, the Zener diode and silicon bridge rectifier. I find it best to flick them both into the bin as my years in business have shown what a problem they can be. I use a Tympanium where possible but Podtronics and others are available. The rectifying and regulating is in one solid state unit and the USA made Typanium, a product that has been around for 40+ years , is a proven reliable replacement. By 1979 Triumphs were 3 phase and negative earth, these 180Watt high output systems are good but not really necessary unless some big headlights for blinding Kangaroos are needed. Especially with low load LED lighting now available the higher output is even less likely to be required , generally a new 2 wire alternator and new rotor will give at least 140 or even 180watts. 3 phase replacements will give up to 220watts.
Carbs now days are in a good place. Amal has their new premier MK 1, Wassell do a good copy and if you aren’t worried about factory look, JRC do a good little Keihin D slide that bolts straight on. There are also Mikuni VM round slides, a carb I have had much experience with and must say it is a goodun with heaps of available jetting, I have a few on my riders. If available I think Dellorto are a good option and I have a few in use. The much more expensive Keihin and Mikuni flat slide are pretty trick and good if you have a top notch high performance special. I have a set of throttle bodies off a modern Triumph triple, with manifold adaptors already made, I hope to one day fit to a T160, but that is a way off, if ever.
I’m a big fan of belt drive primaries especially non unit motor /gearbox assemblies. No more gearbox adjustment to correct primary chain tension. Minimal to no maintenance, set and forget. You may then have the option of going dry so no more oil leaks in the pre-unit era machines. Some belt systems use HTD rubber belts and are only suitable for dry use whereas the polyurethane, polychain belt is oil proof. About 30,000 miles should be easily achievable before a new one is fitted. If you break one the damage is minimal unlike some damage from chains I have seen after they have broken up from lack of oil and adjusting . I have some high mileage on belts and have never had a breakage. Well until recently when a very old belt stripped its teeth on a hot rod motor. The trick with non unit set ups is to install another adjuster on the chain case side to allow a bit of twisting to get a true run. Leaving some slack is very important and If you can twist the belt to at least 45 degrees or a bit more then that is about right. Better a bit loose than too tight. I pretty well only use Taiwan clutch plates and they do a good job wet or dry.
I don’t have a problem with up grading brakes. I have a few that have 4 pot calipers fitted. There is an H-D 4 pot calliper that was designed (copied) after the Lockheed Triumph caliper. It is a direct bolt on and with an adaptor plate common to Norton Norvil stuff , will go on there too. Coupled with a smaller bore Master cylinder, and braided lines it makes a lot of difference. The British factories saw fit to dumb down the first era disc brakes by using 5/8 bore master cylinders , more suitable for a twin disc setup. The smaller bore is best suited to single disc and adds more stopping power. Early disc stuff was no more powerful than a well setup twin leading shoe drum although it did not fade with repeated usage. I remember 30years ago chasing some moderns on my 1972 conical brake 850 Trident. I was keeping up until the downhill section. Poor old cronical gave up after a few hard slow downs, it was comical. The Norton twin leading front brake was the same, a good brake and sometimes better than their first disc offering but would fade compared to the disc under hard use. Extended operating arms on the conical, better linings with correctly radius ground shoes and a machined hub, and a heavier cable can make a difference. I have been using 13mm Magura master cylinders on my 70’s classics for 20 years, sometimes with a modern 4 pot caliper to bring my 70’s machines anchors into this century. I also converted 2 classic Triumphs to hydraulic clutch operation but not with a UK kit which has a hidden piston inside the kicker cover and uses the stock lifting mechanism. I did it by setting an outer cover on the mill, drilling a hole on the mainshaft centre then building up with weld and then a final machine . This puts the push rod inline and lifts direct. Cut up 2 push rods to get the right length and fit a ball between. I use a UJM slave cylinder and an available master cylinder, although a standard Triumph master cylinder can be reversed. Works a treat, one finger light and with a well set up clutch pack, does not slip and this with an 883cc big bore - stroker with at least 60hp +on the ground. This I know, to any naysayers, as I have had it’s less urgent 810cc stable mates on the dyno showing smack on 60hp. Neither having benefitted from head flow work. Humble Triumph pushrod twins. The 883 runs 2 x 38mm carbs and idles. The other stroker big block with the hydraulic clutch is a 4 valve per cyl Rickman top end on unit Triumph cases in an OIFrame, bored and sleeved for a full 850cc.This has been flowed to 92cfm, a full 8cfm more flow than the 2 valve head for my drag bike. I need to finish this thang , it promises to be quicker than both the others. Anyway this is what keeps my juices flowing. Beats sitting on the verandah and wittling. I will soon be trying to do a hydraulic clutch conversion on my Commando as they have a mongrel lifting arrangement which gives a short engage/disengage window.
As for performance with reliability one should start at the bottom. Firstly the cases and if a mild tune is all you want then stock cases in good condition will do. Aftermarket cases exist for Norton and Triumph pre-unit, if you intend to maybe race or just want more useable power and a stronger engine on the street. One piece crankshafts are also available for Norton and Triumph , an instant bulletproof but expensive upgrade . Best thing a mild street performance engine should start with are chrome –moloy or steel conrods. Makers out there have them for lots of twins including A65 and A10 BSA as well as triples , Triumph twins and long (6.3”) or std short rod(5.8”) Norton twins. The long rod in a Norton twin uses a piston whose pin is pushed up and gives longer TDC dwell with increased torque , they are the same rod I use for my Triumph strokers. These rods are marginally heavier than the old alum one but easily dynamically balanced. Moving on up ,camshafts come in all shapes and sizes and some thought must go into this choice. If you want a serious motor the head flow is most important here as it is no sense fitting cams way too big for a heads capability to flow air. In most cases stock cams still work well with mild upgrades to valve and carb sizes. This is a full story on its own. Lightening cam followers ,cam wheels, lightening by polishing rocker arms and fitting lightweight pushrods are all legitimate procedures but usually unnecessary for street use as losing a few kilos off your backside is less time consuming and cheaper. I remember reading somewhere that 12lbs of weight equals 1 hp, true or not?. New valves for most twins are available in stainless with oversizes for reclaiming recessed valve seats and helping with extra flow. The more popular models likeT120- T140 Triumph and Commando have nice forged pistons available. I like to keep street engines at or around 9-1 compression ratio, higher ratios may be good on the track but with todays fuel on the old style hemi combustion chambers 9-1 is a good safe limit.
Bigger is better, no replacement for cubic displacement, I think. No doubt the bigger the engine the less it has to work for a given road speed. So buy a bigger bike or a big bore kit for your 650 Triumph. A Norton crank into a Triumph 650 adds 80cc plus your big bore. An 850 top end on your 750 Norton, with a lot of work it is achievable but start with a good bottom end. Bore and sleeve an 850 Norton cyl block to 920cc. Bore a Trident block for new bigger sleeves and add modified 650 Triumph pistons for 850cc or buy a ready made block. SRM in the UK do a 750cc block for an A65 , fit some MAP chrome –moloy conrods , some 32mm carbs and bingo a stout BSA. Go one better and modify the timing side bush to roller bearing, a Norton crank will go in here with some work and suddenly the humble BSA 650 is a 900 . Bigger does not necessarily mean heaps more HP but will give more torque, the main reason I build bigger engines. This allows me to run higher overall gearing therefore less RPM’s at the same road speed. Running at 60mph with 3000rpm on the tach and with heaps of roll on when required is what I like to have. To get more HP albeit with the added stress it brings, this is where good head work comes in. Flow figures will determine cam types and carb sizes. Sometimes reaching for max flow can upset your low end torque, as can removing too much weight from a crank, not good so a happy medium has to be arrived at for a useable street bike. Too much weight loss from the crank may also make it harder to balance. If the track is your thing then max flow figures and big carbs may be it. In the states in historic racing some of the fastest Triumphs and Nortons use 38mm carbs and Herb Beckers Norton was running up the pointy end of races with 41mm Mikunis. Lots of video of that bike on you tube. This on 750cc bikes being the max size for historic racing there, no methanol in US historic racing either. Big carbs and big cams mean top end power , so you have to keep it on the boil, not very good on the street. Not so with a big bore /stroker. As I said I have an 888cc Triumph big bore/stroker twin that uses 38mm Mikunis , it has romp off the bottom, it is wicked in the mid range and idles. Smaller engines can be made to run as hard or harder than a bigger version of the same engine but will require more revs to do so. Stock 650-750 and 850s are all capable machines and I have done many many miles on them.
Lots of twin shock suspension upgrades can also be had out there in the aftermarket, starting with better quality shocks probably from $500 and up . Brands like Hagon, Progressive, Bitubo, Ikon and at the top of the tree are Penske and Works Performance. All to save that aging back and keep the rear wheel glued to the road. Up front Progressive make nice spring kits for most later British bikes and pre ’70 Triumphs with the large outside springs. Race Tech does a damping and spring kit for OIL in Frame models. With pre ’70 forks on BSAs and Triumph things are a little bit harder to make them dampen better although some mods to the dampers on BSA ‘s were available in the 60’s . On the ‘70s era Triumph and BSA, read OIFrame, a change to RD Yamaha damper rods is a popular conversion on the race track in the US. I have at times made damper rods to mimic OiFrame fork dampers from solid alloy bar and fitted to early pre ’70 Triumph forks, removing the rod operated damper in pre-units or the shuttle valve “damping”. One has to play with drillings a bit but it can be done . I first did it using a modified Oil in Frame damper rod. Norton owners can just buy over the counter at some of the Norton specialists in G.B. Some damping upgrades by welding up and redrilling the damper tube can help. The easy way is to fit a newer type front end that already works, a Ducati or similar ,stock type or upside down, if building a special. I have both in some of my specials and they do the job as they should with no fuss. What about starter motor conversions, available for at least 4 makes, save the knee. Why sell your favourite machine because you can’t start it. Fit a button and save all that money lost to depreciation on a new purchase. Later Matchless singles , Vincent twins, BSA Goldstars and B33’s ,A10 BSA and Norton Commando pre ’75 , a few I know of.
How about doubling the service interval. I fit oil filter housings on the return line to everything I ride and it surprises me how clean the oil still is at the normal change interval of 1000 miles. This then means changing oil and filter every 2000 miles instead. Without a filter your oil is the filter , that is why it gets black, it’s full of carbon from ring blow by. The Commando filter housing are the type I use and it came as standard on 1972 models, mainly because the factory dropped the engine case screen that year, they realised their boo boo and added it back to the new 850 cases the following year. I have been fitting filters to Oil in Frame Triumph and BSA for 20+ years . A simple upgrade using a Harley filter or similar and a modified frame sump plate. Yes it is on the feed but works fine as an oil pressure gauge will tell you.
So there are lots of things to consider for people like me, buy a new one, NAH , I couldn’t use it’s capability, nor am I into long outback riding. I’m into some of the products that abound for classic machinery to upgrade my existing rides. A newer front end with better brakes , top shocks and some engine mods for lazy cruising. Way to go. Much more fun teaching an old dog new tricks.